1. Field
Exemplary embodiments of the present invention relate generally to a semiconductor design technology and, more particularly, to a semiconductor memory device and a semiconductor system including the same.
2. Description of the Related Art
Semiconductor memory devices are categorized into volatile memory devices and nonvolatile memory devices.
A volatile memory device has a relatively high write and read speed, but loses data stored therein when power supply is cut off. On the other hand, a nonvolatile memory device has a relatively low write and read speed, but retains data stored therein when power supply is cut off. Thus, a nonvolatile memory device is used for storing data which must be retained regardless of whether or not power is supplied to the device. Examples of nonvolatile memory devices include ROM (Read Only Memory), MROM (Mask ROM), PROM (Programmable ROM), EPROM (Erasable Programmable ROM), EEPROM (Electrically Erasable Programmable ROM), flash memory, PRAM (Phase change Random Access Memory), MRAM (Magnetic RAM), RRAM (Resistive RAM), and FRAM (Ferroelectric RAM). A flash memory may be a NOR or a NAND type.
A flash memory has not only an advantage of RAM which can freely program or erase data, but also an advantage of ROM which can retain data stored therein even though power supply is cut off. Flash memory is widely used as a storage medium of a portable electronic device, such as a digital camera, a PDA (Personal Digital Assistant), or an MP3 player.
During at least one of a program, read and erase operation, a nonvolatile memory device must set the parameters for performing an operation, for example, word line voltages (that is, a program voltage, a read voltage, and a pass voltage) to be supplied to word lines and a voltage supplied to a bulk (i.e., a well region) in which memory cells are formed, before performing an operation corresponding to each command. Thus, when a command is received, the overall operation time is increased due to the time required for setting the parameters needed for performing an operation corresponding to the received command.
Thus, there is a demand for a scheme for improving the overall operation performance of a semiconductor device such as a flash memory device by reducing the time required for setting the parameters needed for performing an operation corresponding to a received command.